The United States lashed out on Thursday at "predatory" Chinese and Russian policy in Africa and unveiled a new strategy for using economic muscle to counter its rivals' grips on the continent.

An increasingly assertive Beijing and Moscow "pose a significant threat to US national security interests" in resource-rich Africa, White House national security advisor John Bolton said in a speech he was to deliver later.

Their "predatory practices" stunt economic growth and independence, while hampering US trade and military goals, he said in the text of the speech previewed by AFP.

China in particular has made dramatic inroads in Africa with direct investment, aid and infrastructure projects that leave partners burdened by heavy debt - and under long-term Chinese influence.

At a time when the Pentagon wants to reduce its Africa footprint, the United States says its best weapon in the power struggle will be to build partnerships through trade.

African governments will from now on find a tighter-fisted approach to traditional aid, Bolton said, with an end to "indiscriminate assistance across the entire continent."

A senior Trump administration official said there is longtime US "frustration" with corrupt African aid recipients.